Method and device for removing disk brake pistons

ABSTRACT

Each of the brake pistons within a disk brake caliper is removed therefrom for overhaul by increasing liquid pressure applied thereto until the piston is released from the caliper. When more than one piston is mounted in a caliper and the pistons are liquid connected to each other, all of the pistons except one are retained within the caliper by suitable means so that only the one piston can respond to the increasing liquid pressure.

[ Mar. M, i972 United States Patent SimmondsKuniholm......................

Miaskiewicz...................:......

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211 App]. No.: 857,290

Primary Examiner-Charlie T. Moon Attorney-Kinney and Schenk Related US.Application Data [63] Continuation-impart of Ser. No. 764,423, Oct. 2,

ABSTRACT Each of the brake pistons within a disk brake caliper is 1968,abandoned.

removed therefrom for overhaul by increasing liquid pressure 29/200applied thereto until the piston is released from the caliper. I427188/72 5 When more than one piston is mounted in a caliper and thepistons are liquid connected to each other, all of the pistons exceptone are retained within the caliper by suitable means so that only theone piston can respond to the increasing liquid pressure.

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References Cited UNlTED STATES PATENTS McKay.......t........................29/427 X 15 Claims, 15 Drawing Figures PATENTEDMAR 14 m2SHEET 1 (IF 7 INVENTOR. SILAS E. SIMMONDS PATENTEDMAR 14 1912 3, 648,352

SHEET 2 OF 7' .IIVVEN TOR. SILAS E. SIMMONDS PATENTEUMAR 14 m2 3, 6A8 35 2 SHEET 3 UF 7 awso AHHHHII SILAS E. SHMMONDS Pmmwmm m2 3,6d8,352

SHEET or 7 INVENTOR. SILAS E. SIMMONDS I ATTORNEYS;

PATENTEDMAR M 1972 3, 6A8 352 SHEET 5 OF 7 INVENTOR ATTORNEYSPATENTEUHAR 14 I972 SHEET 8 [1F 7 INVENTOR FEGDW SILAS E. SIMMONDSATTORNEYS PATENTEDHAR 14 m2 3, 648 352 SHEET 7 [1F 7' INVENTOR SILAS E.SHMMONDS ATTORNEYS METHOD AND DEVICE FOR REMOVING DISK BRAKE PISTONSThis application is a continuation-in-part of application Serial No.764,423, filed Oct. 2, 1968, now abandoned.

In disk brakes, the friction pads or shoes, which engage the rotatingdisk, are removably carried by a caliper. In one type of disk brake, thecaliper has a pair of oppositely facing pistons disposed therein foracting on the friction pads that are on opposite sides of the rotarydisk. As a result, when liquid supplied to the caliper, both of thepistons are simultaneously moved toward each other to urge the frictionpads against the rotary disk to produce the desired braking action.

When overhauling this type of disk brake, it is necessary to remove theoppositely facing pistons after the friction pads have been removed fromthe caliper. This is necessary to inspect the piston to determine if itneeds replacing due to having become pitted, for example. Likewise, itis desirable to replace the external seal on the piston.

Because each of the pistons has the external seal cooperating with thewall of the cylinder in which it is disposed, it is difficult to removethe pistons from the caliper. This is particularly true if the pistonhas rusted within the caliper and become frozen therein.

A present method utilized for removing the disk brake pistons from thecaliper has been to apply air pressure to the pistons simultaneously.However, because relatively low air pressure is used, this is timeconsuming and has required as long as 6 hours to remove each of thehollow brake pistons. This is also because the hollow piston may tend torust within the caliper so that a very high pressure is necessary toremove the piston from the caliper.

Frequently the pistons are so tightly engaged in the calipers that theycannot be removed by compressed air normally used in service stationswhere air pressures are deliberately low to avoid injury to bystanders.

For instance, in many cases between 500 and 1,000 pounds pressure isrequired, but if this pressure is applied from a com pressed air source,the piston would release with such explosive force that it might easilyinjure or kill a bystander or damage property.

By contrast, when a liquid is used the pressure force is not explosiveand the pressure is released without explosive action when the piston isremoved from the caliper.

The present invention satisfactorily overcomes the foregoing problem byproviding a method and device for easily removing disk brake pistonsfrom a caliper. Thus, even if the piston has rusted within the caliperand become frozen therein, the present invention easily andsatisfactorily removes it in a short period of time such as to minutes,for example. Accordingly, the time required when using the method anddevice of the present invention to remove the rusted piston is onlyabout 4 percent of the time required when using the previously availablemethod.

In another type of disk brake, the caliper has two pairs of oppositelyfacing pistons disposed therein for acting on the friction pads that areon opposite sides of the rotary disk. In this type of disk brake, thesupply of fluid to the caliper causes all of the pistons to besimultaneously moved toward each other to urge the friction pads againstthe rotary disk to produce the desired braking action.

In this type of disk brake, the present invention is equallysatisfactory. When the caliper has two pair of oppositely facing andfluid connecting pistons, only one of the pistons may be responsive tothe increasing liquid pressure applied to the caliper at any one time.The present invention satisfactorily meets this requirement by providinga pair of cooperating members that prevent the other three of the fourpistons from being responsive to the liquid pressure.

In some disk brakes, only a single piston is mounted in a caliper.Again, the present invention satisfactorily enables this type of pistonto be removed from the caliper by applying an increasing liquid pressureto the piston.

An object of this invention is to provide a method for removing a diskbrake piston from a caliper.

Another object of this invention is to provide a method and device forremoving oppositely facing disk brake pistons from a caliper.

Another object is to create a device for removing pistons from thecalipers of disc brakes which will be safe to use by the ordinarymechanic.

Other objects, uses, and advantages of this invention are apparent upona reading of this description, which proceeds with reference to thedrawings forming part thereof and wherein:

FIG. 1 is a side elevational view of one form of the device of thepresent invention for removing oppositely facing disk brake pistons froma caliper.

FIG. 2 is a front elevational view of the device of FIG. ll.

FIG. 3 is an enlarged top plan view, partly in section, of the deviceofFIG. 1.

FIG. 4 is an enlarged sectional view illustrating the reservoir and pumpmeans of the device of FIG. l. v

FIG. 5 is a side elevational view, partly in section, showing the checkvalve that prevents reverse flow of liquid from the caliper to theliquid reservoir.

FIG. 6 is an enlarged perspective view showing a clamp for retaining oneof the oppositely facing pistons within the caliper while the other isbeing removed.

FIG. 7 is a sectional view illustrating the mounting ofthe caliper onthe support structure of the device.

FIG. 8 is a side elevational view, partly in section, showing themounting of a liquid collection or drain pan.

FIG. 9 is a top plan view of another form of the device of the presentinvention in which two pairs of oppositely facing disk brake pistons areremoved from a caliper.

FIG. 10 is an enlarged perspective view showing a clamp for retainingtwo of the four pistons in the caliper of FIG. 9 while one of the othertwo pistons is being removed.

FIG. 11 is an enlarged perspective view showing another clamp forretaining one of the other two of the four pistons within the caliper ofFIG. 9 while the remaining piston is being removed.

FIG. 12 is a side elevational view of one form of connector between theliquid pressure line and the caliper.

FIG. 13 is an elevational view, partly in section, of another form ofconnector between the liquid pressure line and the caliper.

FIG. 14 is a top plan view of a caliper in which only a single piston isemployed with the caliper having a liquid pressure line connectedthereto for removing the single piston from the caliper by the method ofthe present invention.

FIG. 15 is a top plan view of another caliper having only a singlepiston mounted therein with the caliper having a liquid pressure lineconnected thereto for removing the single piston from the caliper by themethod ofthe present invention.

Referring to the drawings and particularly FIGS. 1 to 3, there is showna caliper 10 that has been removed from a motor vehicle. The frictionpads or shoes also have been removed from the caliper 10.

The caliper 10 has a space 11 (see FIG. 1) formed therein between spacedportions of the caliper 10 to allow the rotary disk to rotatetherethrough when the caliper 10 is mounted on the motor vehicle.Oppositely facing pistons 12 and 13 (see FIG. 3) are slidably mounted incylinders within the caliper 10. The caliper 10 has liquid passagestherein to provide liquid communication between the two cylinders withinwhich the pistons 12 and 13 are slidably mounted.

The pistons 12 and 13 extend into an enlarged recess 14 i (see FIG. 3)within the caliper 10. The lower end of the recess 14 communicates withthe upper end of the space 11 so that a portion of the rotary diskrotates through the bottom of the recess 14.

Accordingly, when liquid is supplied to the caliper 10 through a fittingwhen the caliper 10 is mounted on the motor vehicle, the pistons 12 and13 are moved simultaneously toward each other. Since each of the pistons12 and 13 moves a friction pad (not shown), which is mounted within therecess 14, into engagement with the rotary disk, application of liquidthrough the fitting 15 results in the rotary disk being engaged by thefriction pads. The caliper has a bleed valve 16 (see FIG. I) mountedthereon to permit removal of any air from the liquid system of thecaliper 10.

When the caliper 10 is to have the pistons 12 and 13 removed therefromfor overhaul, the method of the present invention contemplates mountingthe caliper 10 on a frame 17, which may be fixedly secured to a workbench 18, for example, by a vise 19. Thus, the frame 17 is fixedlysupported. Of course, any other suitable means for placing the caliper10 in a fixed position may be utilized.

The caliper 10 is mounted on the frame 17 through having an ear 20,which is utilized in mounting the caliper 10 on the motor vehicle,attached to the frame 17 by a bolt 21 and nut 22. A threaded sleeve 23(see FIG. 7) is disposed between the ear 20 and the frame 17 to spacethe caliper 10 from the frame 17.

A reservoir 24 is fixedly attached to the frame 17 beneath the caliper10. As shown in FIG. 4, the reservoir 24 has a filler pipe 25 with a cap26 thereon. Thus, brake liquid may be supplied to the reservoir 24 byremoving the cap 26 whereby he desired amount of liquid is providedwithin the reservoir 24.

As shown in FIG. 4, the reservoir 24 has a chamber 27 thereincommunicating with the filler pipe 25 through an opening 28 in one endof a wall defining the chamber 27. A spring 29 is disposed within thechamber 27 and continuously urges a piston 30 to the right (as viewed inFIG. 4). A rod 31 is connected to the piston and extends beyond theframe 17. Liquid leakage is prevented by a seal 32 at one end of thechamber 27; the rod 31 extends through the seal 32.

As shown in FIG. 1, the piston rod 31 has its other end connected to alever 33 through a pin and slot arrangement. Thus, when the lever 33,which is pivotally mounted on an ear 34 of the frame 17 by a pin 35, ismoved toward the frame 17, the piston 30 is moved toward the left (asviewed in FIG. 4) against the force of the spring 29. This pumps liquidfrom the reservoir 24 through a hose 36 that communicates with thefitting of the caliper 10. Thus, the liquid, which is pumped from thereservoir 24 by the piston 30, is supplied to the liquid passages in thecaliper 10.

As shown in FIG. 5, the hose 36 has a valve 37 mounted therein toprevent reverse flow of liquid to the reservoir 24. A spring 38continuously urges the check valve 37 to a closed position to preventliquid flow to the reservoir 24 from the caliper 10. When liquid fromthe reservoir 24 isbeing pumped to the caliper 10, the check valve 27 isnot effective since the pressure of the liquid being pumped from thereservoir 24 overcomes the force of the spring 38.

The frame 17 has a collection or drain pan 39 mounted thereon beneaththe caliper 10. The pan 39 collects liquid when the piston 12 or 13 isremoved from the caliper 10. The pan 39 is removably mounted on theframe 17 by a spring clip 40.

In order to retain one of the oppositely facing pistons 12 and 13 sothat it cannot respond to the liquid pressure supplied to the liquidpassages in the caliper 10 from the reservoir 24, a clamp 41 (see FIG.6) is utilized. The clamp 41 includes a U- shaped portion 42 on one end.The U-shaped portion 42 has legs 43 and 44 with pointed ends thereon.The U-shaped portion 42 is adapted to be disposed within the enlargedrecess 14 in the caliper 10.

When the U-shaped portion 42 of the clamp 41 is disposed within therecess 14 in the manner shown in FIG. 3, the U- shaped portion 42 hasits surface 46 bearing against the piston 13. Since the castings, whichform the caliper 10, may be rough, the pointed ends of the legs 43 and44 permit the U- shaped portion 42 of the clamp 41 to be forced into therecess 14 if necessary.

As shown in FIG. 6, the U-shaped portion 42 has an upwardly extendingportion 47 connected at its upper end to a longitudinal support portion48, which rests on a portion of the caliper 10. The longitudinal portion48 has a connecting portion 49, which is substantially parallel to theportion 47, attached thereto.

The clamp 41 also includes a handle portion 50, which is parallel to thesupport portion 48 and connected to the lower end of the connectingportion 49. Thus, the clamp 41 may be easily handled for insertion andremoval from the recess 14.

In carrying out the method of the present invention, the caliper 10 isfirst removed from the vehicle and is cleaned. Next, the hose 36 isconnected to the fitting 15 of the caliper 10. The caliper 10 is thenmounted on the frame 17 by the bolt 21, the nut 22, and the threadedsleeve 23.

The clamp 41 is then installed within the caliper 10 so as to retain thepiston 13 in the retracted position of FIG. 3. The reservoir 24 is nextfilled with liquid. The lever 33 is then actuated to pump liquid fromthe reservoir 24 to the liquid passages in the caliper 10. If there isany air within the liquid passages in the caliper 10, the bleed valve 16is opened to bleed the air therefrom.

With the collection or drain pan 39 positioned beneath the caliper 10,the lever 33 pumps liquid from the reservoir 24 to the caliper 10 bymeans of the piston 30. As the pressure in the liquid passages in thecaliper 10 increases, the piston 12 is eventually removed from thecaliper 10 even if the piston 12 is frozen within the cylinder in thecaliper 10. Through the lever 33, the pressure acting on the piston 12may be increased to 850 or more pounds pressure. With only the piston 12being movable, the effective pressure on the piston 12 is greater thanduring braking when both of the pistons 12 and 13 are movable.

When the piston 12 is pushed out of the cylinder within the caliper 10,the liquid within the liquid'passages in the caliper 10 and in the hose36 escapes through the removed piston 12 and is caught by the pan 39.The pan 39 is then removed from the frame 17 and liquid discarded.

With the piston 12 removed, the caliper 10 is cleaned and the piston 12is inspected. If necessary, the piston is replaced. Then, the old or newpiston is installed within the cylinder in the caliper 10 with a newseal.

With the piston 12 installed within the cylinder in the caliper 10, theclamp 41 is removed from retaining the piston 13 in its retractedposition. The clamp 41 is now positioned in the opposite direction tothat shown in FIG. 3 so that it retains the piston 12, either new orreconditioned, in its retracted position. Then, the method is repeatedfor removing the piston 13 from the caliper 10. Thereafter, the caliper10 is removed from the frame 17 and again installed on the motorvehicle.

Referring to FIG. 9, there is shown a caliper 51 that has been removedfrom a motor vehicle. The friction pads or shoes also have been removedfrom the caliper 51.

The caliper 51 has a space formed therein between spaced portions of thecaliper 51 in the same manner as the caliper 10 has the space 11 toallow the rotary disk to rotate therethrough when the caliper 51 ismounted on the motor vehicle. Four pistons 52-55 are slidably mounted incylinders within the caliper 51. The pistons 52 and 53 comprise a firstpair of oppositely facing pistons, and the pistons 54 and 55 comprise asecond pair of oppositely facing pistons.

The caliper 51 has liquid passages therein to provide liquidcommunication between the four cylinders within which the pistons 52-55are slidably mounted. One of the liquid passages is shown at 56 andcommunicates through a passage 57 with the interior of the cylinderwithin which the piston 52 is slidably mounted.

The pistons 52-55 extend into an enlarged recess 58 within the caliper51. The lower end of the recess 50 communicates with the upper end ofthe space through which the upper end of the space through which therotary disk rotates so that a portion of the rotary disk rotates throughthe bottom of the recess 58.

Accordingly, when liquid is supplied to the caliper 51 through a fittingwhen the caliper 51 is mounted on the motor vehicle, the pistons 52 and53 are moved simultaneously toward each other, and the pistons 54 and 55are moved simultaneously toward each other. Since each of the pistons52-55 moves a friction pad (not shown), which is mounted within therecess 58, into engagement with the rotary disk, ap-

plication of liquid through the fitting results in the rotary disk beingengaged by the friction pads. The caliper 51 has a bleed valve (notshown) mounted thereon to permit removal of any air from the liquidsystem of the caliper 51.

When the caliper 51 is to have the pistons 52-55 removed therefrom foroverhaul, the method of the present invention contemplates disposing thecaliper 51 within a collection or drain pan 60. The pan 60 collectsliquid when one of the pistons 52-55 is removed from the caliper 51.

The caliper 51 is connected to the hose 36, which has liquid suppliedthereto under pressure from the reservoir 24 in the manner previouslydescribed. The hose 36 is connected to the caliper 51 through aconnector, which has one end communicating with the fitting of thecaliper 51 and its other end communicating with the hose 36.

Referring to FIGS. 12 and 13, there are shown two forms of connectors.As shown in FIG. 12, a connector 61 has one end clamped over the end ofthe hose 36 while its other end is adapted to be disposed within thefitting in the caliper 51 for connection thereto.

A second form of connector 62 is shown in FIG. 13 and is utilized whenthe caliper 51 has a fitting that is much larger in diameter than thefitting with which the connector 61 is utilized. Either of theconnectors 61 and 62 provides a liquid connection between the hose 36and the liquid passages within the caliper 51.

In order to retain all but one of the pistons 52-55 so that they cannotrespond to the liquid pressure supplied to the liquid passages (oneshown at 56) in the caliper 51 from the reservoir 24, large clamp orfork 68 (see FIG. and a small clamp or fork 69 (see FIG. 11) areutilized. As shown in FIG. 9, the clamp 68 cooperates with two of thepistons on the same longitudinal side of the recess 58 while the clamp69 cooperates with one of the two pistons on the other longitudinal sideof the recess 58 so as to leave one of the four pistons 52-55 free tomove in response to the liquid pressure.

The clamp 68 includes a U-shaped portion 70 (see FIG. 10) on one endthereof. The U-shaped portion 70 has legs 71 and 72 with pointed endsthereon. The U-shaped portion 70 is adapted to be disposed within theenlarged recess 58 in the caliper 51.

When the U-shaped portion 70 of the clamp or fork 68 is disposed withinthe recess 58 in the manner shown in FIG. 9, the U-shaped portion 70 hasits surface 73 hearing against the pistons 53 and 55. Since thecastings, which form the caliper 51. may be rough, the pointed ends ofthe legs 71 and 72 permit the U-shaped portion 711 of the clamp 68 to beforced into the recess 58 is necessary.

As shown in FIG. 10, the U-shaped portion 70 has an upwardly extendingportion 74 connected at its upper end to a support portion 75, whichrests on a portion of the caliper 51. The support portion 75 has aconnecting portion 76, which is substantially parallel to the upwardlyextending portion 74, attached thereto.

The clamp 68 also includes a handle portion 77, which is parallel to thesupport portion 75 and connected to the lower end of the connectingportion 76. Thus, the clamp 68 may be easily handled for insertion andremoval from the recess 58.

The clamp 68 is substantially similar to the clamp 41 shown in FIG. 6.The primary distinction is that the base of the U- shaped portion 70 ofthe clamp 68 is much longer than the base of the U-shaped portion 42 ofthe clamp 41. This is to cooperate with two pistons rather than a singlepiston.

The clamp 69 includes a rectangular shaped portion 78, which is adaptedto engage one of the pistons to retain it within the caliper 51 whenliquid pressure is supplied to the caliper 51 from the reservoir 24. Asshown in FIG. 9, the rectangular shaped portion 78 of the clamp 69 isengaging the piston 54. Thus, the piston 52 is free to respond to theliquid pressure supplied to the caliper 51.

The clamp 69 also includes a base portion 79, which carries therectangular shaped portion 78 thereon. As shown in FIG. 9, the baseportion 79 is disposed between the base of the U- shaped portion 70 ofthe clamp 68 and the rectangular shaped portion 78. A finger 80 extendsfrom the base portion 79 over the top of the rectangular shaped portion78 and over the top of the caliper 51 so that the finger portion 80rests on the caliper 51.

In carrying out the method of the present invention, the caliper 51 isfirst removed from the vehicle and is cleaned. Next, the hose 36 isconnected to the fitting of the caliper 51 through one of the connectors61 and 62 depending upon the type of fitting on the caliper 51. At thistime, the caliper 51 is disposed within the collection pan 60.

The clamp 68 is then installed within the recess 58 in the caliper 51 soas to retain the pistons 53 .and 55 in the retracted position of FIG. 9.The clamp 69 is next disposed within the recess 58 in the caliper 51 toretain the piston 54 in the retracted position of FIG. 9.

The reservoir 24 is next filled with liquid. The lever 33 is thenactuated to pump liquid from the reservoir 24 to the liquid passages(one shown at 56) in the caliper 51. If there is any air within theliquid passages in the caliper 51, the bleed valve (not shown) on thecaliper 51 is opened to bleed the air therefrom.

Liquid is pumped from the reservoir 24 to the caliper 51 by means of thepiston 30 due to actuation ofthe lever 33. As the pressure in the liquidpassages in the caliper 51 increases, the piston 52 is eventuallyremoved from the caliper 51 even if the piston 52 is frozen within thecylinder in the caliper 51. Through the lever 33, the pressure acting onthe piston 52 may be increased to 500 or more pounds pressure. With onlythe piston 52 being movable, the effective pressure on the piston 52 isgreater than during braking when all the pistons 52-55 are movable.

When the piston 52 is pushed out of the cylinder within the caliper 51,the liquid within the liquid passages in the caliper 51 and in the hose36 escapes through the removed piston 52 and is caught in the pan 60.The caliper 51 is removed from the pan 60 to allow the liquid to bediscarded.

With the piston 52 removed, the caliper 51 is cleaned, and the piston 52is inspected. If necessary, the piston is replaced. Then, the old or newpiston is installed within the cylinder in the caliper 51 with a newseal.

With the piston 52 installed within the cylinder in the caliper 51, theclamp 69 is removed from retaining the piston 54 in its retractedposition. The clamp 69 is now positioned to retain the piston 52, eithernew or reconditioned, in its retracted position. Then, the method isrepeated to remove the piston 54 from the caliper 51.

After the piston 54, either new or reconditioned, has been installedwithin the cylinder in the caliper 51, the clamps 68 and 69 are removedfrom the recess 58. Then, the clamp 68 is disposed so that the pistons52 and 54 are retained in the retracted position by the clamp 68. Theclamp 69 is then positioned to retain one of the pistons 53 and 55 inits retracted position. If it be assumed that the clamp 69 is retainingthe piston 55, then the method is repeated to remove the piston 53 fromthe caliper 51.

With the piston 53 installed within the cylinder in the caliper 51, theclamp 69 is removed from retaining the piston 55 in its retractedposition. The clamp 69 is now positioned to retain the piston 53, eithernew or reconditioned, in its retracted position. Then, the method isrepeated to remove the piston 55 from the caliper 51. Thereafter, thecaliper 51 is installed on the motor vehicle.

Referring to FIG/ 14, there is shown a caliper 81, which has a singlepiston 82 movable therein for cooperation with a rotary disk. The singlepiston 82 is movable into a recess 83 in the caliper 81 to engage therotary disk. The piston 82 has a friction pad thereon that cooperateswith the rotary disk. Only the single piston 82 is employed to stoprotation of the rotary disk.

IN carrying out the method of the present invention with the caliper 81,the caliper 81 is first removed from the vehicle and is then cleaned.Next, the hose 36 is connected to the fitting of the caliper 81 throughone of the connectors 61 or 62. The caliper 81 is then disposed withinthe collection or drain pan 60.

The reservoir 24 is next filled with liquid. The lever 33 is thenactuated to pump liquid from the reservoir 24 to the liquid passages inthe caliper 81. If there is any air within the fluid passages in thecaliper 81, a bleed valve (not shown) on the caliper 81 is opened tobleed the air therefrom.

With the collection or drain pan 60 having the caliper 81 positionedtherein, the lever 33 pumps liquid from the reservoir 24 to the caliper81 by means of the piston 30. As the pressure in the liquid passages inthe caliper 81 increases, the piston 82 is eventually removed from thecaliper 81 even if the piston 82 is frozen within the cylinder in thecaliper 81.

In order to obtain a more effective pressure on the piston 82 than isavailable during the braking action, it is necessary that the pressureacting on the piston 82 be greater than the pres sure applied duringbraking action since there is only the single piston. Thus, it isdesirable that the pressure supplied to the piston 82 by the lever 33 begreater than in the prior embodiments.

When the piston 82 is pushed out of the cylinder within the caliper 81,the liquid within the liquid passages in the caliper 81 and in the hose36 escapes through the removed piston 82 and is caught by the pan 60.After the caliper 81 is removed from the pan 60, the liquid is removedfrom the pan 60.

With the piston 82 removed, the caliper 81 is cleaned, and the piston 82is inspected. if necessary, the piston is replaced. Then, the old or newpiston is installed within the cylinder in the caliper 81 with a newseal. The caliper 81 is then mounted on the vehicle.

Referring to FIG. 15, there is shown a caliper 84 having a single piston85 slidably mounted therein. The piston 85 carries a friction padthereon. The friction pad is mounted on the piston 85 by means of amounting hook 86.

When using the caliper 84 with a rotary disk, two of the calipers 84 arerequired with one disposed on each side of the rotary disk. Thus, bysimultaneously applying liquid to both of the calipers 84, the pistons85, which are oppositely disposed, are moved toward each other to clampthe rotary disk therebetween. However, each of the calipers 84 isseparate so that each of the pistons 85 must be removed from its caliper84 separately.

In carrying out the method of the present invention with each of thecalipers 84, the caliper 84 is first removed from the vehicle and iscleaned. Next, the hose 36 is connected to the fitting of the caliper 84through one of the connectors 61 or 62. The caliper 84 is then placedwithin the collection or drain pan 60.

Thereafter, the method is the same as that described for the caliper 81.This results in the piston 85 being removed from the caliper 84.

An advantage of this invention is that it reduces the time to remove thepistons ofa power disk brake from the caliper for overhaul. Anotheradvantage of this invention is that it decreases the cost of overhaulinga power disk brake.

For purposes of exemplification, particular embodiments of the inventionhas been shown and described according to the best present understandingthereof. However, it will be apparent that changes and modifications inthe arrangement and construction of the parts thereof may be resorted towithout departing from the spirit and scope of the invention.

What is claimed is:

l. The method of removing a piston from within a disk brake caliper of avehicle, the method including first removing the caliper from thevehicle, supplying liquid under pressure from an external source to thecaliper to act, directly upon said piston, so that said piston canrespond to said pressure and increasing the pressure of the liquid onthe piston until the piston is removed from the caliper.

2. The method according to claim 1 in which any air is bled from theliquid lines in the caliper when liquid is initially supplied thereto.

3. A method for removing each of a plurality of liquid connected pistonsfrom a caliper in which the pistons are slidably mounted, the methodincluding supplying liquid under pressure to the caliper to act on allof the pistons, holding all of the pistons but one of the pistons sothat only the one piston can respond to the liquid pressure applied toall of the pistons, and increasing the pressure of the liquid acting onthe pistons until the one piston is removed from the caliper.

4. The method according to claim 3 in which any air is bled from theliquid lines in the caliper when liquid is initially supplied thereto.

5. The method according to claim 3 in which the caliper has a pair ofoppositely disposed pistons slidably mounted therein.

6. The method according to claim 3 in which the caliper has two pairs ofoppositely disposed pistons slidably mounted therein.

7. A including for removing from a caliper at least one pair ofoppositely facing pistons that are liquid connected to each othercomprisingv means to lock all but one of the pistons within the caliperin a retracted position, means to supply liquid pressure to all of thepistons, and said supply means including means to increase the liquidpressure until the one piston is forced from the caliper.

8. The device according to claim 7 in which the caliper has two pairs ofoppositely disposed pistons slidably mounted therein.

9. The device according to claim 7 including means to support thecaliper.

10. The device according to claim 7 in which said supply means includesa liquid reservoir, means connecting said liquid reservoir to thecaliper, and means to pump the liquid from said reservoir through saidconnecting means to the caliper.

11. The device according to claim 10in which said connecting meansincludes a check valve to prevent reverse flow of liquid to saidreservoir.

12. The device according to claim 10 including means to support saidliquid reservoir and the caliper thereon.

13. The device according to claim 12 including means mounted on saidsupport means beneath the caliper to collect any liquid from thecaliper.

14. The device according to claim 11 in which said pumping meansincludes a piston slidably mounted in said reservoir and means toactuate said piston.

15. The device according to claim 12 in which said pumping meansincludes a piston slidably mounted in said reservoir and means pivotallymounted on said support means to actuate said piston.

1. The method of removing a piston from within a disk brake caliper of avehicle, the method including first removing the caliper from thevehicle, supplying liquid under pressure from an external source to thecaliper to act, directly upon said piston, so that said piston canrespond to said pressure and increasing the pressure of the liquid onthe piston until the piston is removed from the caliper.
 2. The methodaccording to claim 1 in which any air is bled from the liquid lines inthe caliper when liquid is initially supplied thereto.
 3. A method forremoving each of a plurality of liquid connected pistons from a caliperin which the pistons are slidably mounted, the method includingsupplying liquid under pressure to the caliper to act on all of thepistons, holding all of the pistons but one of the pistons so that onlythe one piston can respond to the liquid pressure applied to all of thepistons, and increasing the pressure of the liquid acting on the pistonsuntil the one piston is removed from the caliper.
 4. The methodaccording to claim 3 in which any air is bled from the liquid lines inthe caliper when liquid is initially supplied thereto.
 5. The methodaccording to claim 3 in which the caliper has a pair of oppositelydisposed pistons slidably mounted therein.
 6. The method according toclaim 3 in which the caliper has two pairs of oppositely disposedpistons slidably mounted therein.
 7. A device for removing from acaliper at least one pair of oppositely facing pistons that are liquidconnected to each other comprising means to lock all but one of thepistons within the caliper in a retracted position, means to supplyliquid pressure to all of the pistons, and said supply means includingmeans to increase the liquid pressure until the one piston is forcedfrom the caliper.
 8. The device according to claim 7 in which thecaliper has two pairs of oppositely disposed pistons slidably mountedtherein.
 9. The device according to claim 7 including means to supportthe caliper.
 10. The device according to claim 7 in which said supplymeans includes a liquid reservoir, means connecting said liquidreservoir to the caliper, and means to pump the liquid from saidreservoir through said connecting means to the caliper.
 11. The deviceaccording to claim 10 in which said connecting means includes a checkvalve to prevent reverse flow of liquid to said reservoir.
 12. Thedevice according to claim 10 including means to support said liquidreservoir and the caliper thereon.
 13. The device according to claim 12including means mounted on said support means beneath the caliper tocollect any liquid from the caliper.
 14. The device according to claim11 in which said pumping means includes a piston slidably mounted insaid reservoir and means to actuate said piston.
 15. The deviceaccording to claim 12 in which said pumping means includes a pistonslidably mounted in said reservoir and means pivotally mounted on saidsupport means to actuate said piston.